Modern molecular testing for infections, STIs and disturbances of the vaginal flora
Genital tract infections may cause symptoms such as vaginal discharge, itching, burning, discomfort or recurrent vaginitis. In other cases, certain pathogens may be present without obvious symptoms.
Molecular testing of a vaginal sample using Real-Time PCR allows a large number of microorganisms to be investigated simultaneously from a single sample. This particular panel tests for a total of 28 microorganisms and markers of the vaginal flora, including pathogens associated with sexually transmitted infections, Candida species and microorganisms associated with bacterial vaginosis.
Important: This testing does not mean that all 28 microorganisms are sexually transmitted diseases. Some may form part of the normal flora or be detected as colonisation without causing disease.
What is molecular testing by PCR?
PCR is a molecular method that looks for the genetic material of specific microorganisms in the sample.
The test used for this particular panel involves the isolation of genetic material, followed by Real-Time Polymerase Chain Reaction – Real-Time PCR. The reagents used are certified for in vitro diagnostic use (CE-IVD).
This is therefore a molecular test rather than a conventional vaginal fluid culture.
Which microorganisms does it test for?
| Category | Microorganisms included |
|---|---|
| STIs and genital tract infections | Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum, Ureaplasma parvum |
| Genital ulcer pathogens / viruses | Herpes simplex virus 1, Herpes simplex virus 2, Treponema pallidum, Haemophilus ducreyi, Lymphogranuloma venereum, Cytomegalovirus, Varicella-zoster virus |
| Candida (A type of fungus) | Candida albicans, C. glabrata, C. lusitaniae, C. tropicalis, C. krusei, C. parapsilosis, C. dubliniensis |
| Vaginal flora / bacterial vaginosis | Gardnerella vaginalis, Atopobium vaginae, Megasphaera type 1, BVAB2, Mobiluncus spp., Bacteroides fragilis, Lactobacillus spp. |
The panel is therefore not limited to conventional STIs, but also provides information about Candida and the microbial profile associated with bacterial vaginosis.
When can testing be useful?
The decision to perform molecular testing is made after assessing the medical history and clinical presentation.
It may be used as part of an investigation when there is a suspected genital tract infection, symptoms of vaginitis, persistent or recurrent symptoms, or a need to investigate a specific sexually transmitted pathogen.
Not every woman needs to undergo the entire panel. The appropriate test should be selected individually by the treating physician.
How is the test performed?
The test is performed by collecting a sample (cellular swab) from the genital tract. In practice, this is the same procedure we follow when collecting a sample for a Pap test
Sample collection is brief, and the sample is then sent to the laboratory for molecular analysis using Real-Time PCR.
Is any preparation required?
The exact instructions depend on the type of sample and the reason for testing. For this reason, individual instructions are provided before sample collection.
What does a positive result mean?
A positive PCR result means that genetic material from the specific microorganism has been detected.
However, it does not always mean that this microorganism is the cause of the symptoms.
The laboratory protocol itself clarifies that a positive result does not, on its own, prove that the detected pathogen is the causative agent of the disease, and that the result must be considered alongside the clinical presentation.
This is particularly important for microorganisms such as Mycoplasma hominis, Ureaplasma spp., Gardnerella vaginalis, Atopobium vaginae and other organisms that may also be detected in women without an active infection.
For this reason:
A positive PCR result does not automatically mean that treatment is required.
The physician interprets the result, taking into account the specific microorganism, the symptoms, the clinical examination and the rest of the medical history. The laboratory itself points out that some microorganisms in the panel may form part of the normal flora or be detected in healthy, asymptomatic individuals.
What if the result is negative?
A negative result means that the specific microorganism was not detected above the detection limits of the method in that particular sample.
However, it does not rule out every possible infection. The laboratory explicitly states that a negative result does not rule out infection with a pathogen that is not included in this particular panel.
The sensitivity of the test may also be affected by the sampling method, the stage of the infection and substances that may inhibit the PCR reaction.
PCR or a standard vaginal fluid culture?
PCR and conventional vaginal fluid culture are not competing tests; they answer different questions and, in some cases, both may be needed.
PCR directly looks for genetic material from specific microorganisms included in the panel. It is particularly useful when we want to test for pathogens that are NOT easily detected by a standard culture, or when high diagnostic sensitivity is required, such as for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis or Mycoplasma genitalium. For chlamydia and gonorrhoea, molecular NAAT/PCR methods are key diagnostic tests and generally have higher sensitivity than culture.
Culture, in contrast, relies on the growth of living microorganisms in the laboratory. Its important advantage is that, when a specific bacterium or fungus is isolated, antibiotic or antifungal susceptibility testing may follow in appropriate cases. This is particularly useful when there is a persistent or recurrent infection and the initial treatment has not been effective.
Frequently asked questions
The panel includes 28 microorganisms or microbiological markers. Some of these are conventional sexually transmitted pathogens (STIs), but we also test for Candida (a type of fungus), microorganisms associated with bacterial vaginosis and Lactobacillus spp.
Not necessarily. The detection of certain microorganisms may represent colonisation rather than an active infection. The result must be considered alongside the symptoms and clinical presentation.
Not on its own. This particular panel also assesses Lactobacillus spp., Gardnerella vaginalis and Atopobium vaginae to establish a molecular profile of bacterial vaginosis. Gardnerella and Atopobium may be detected in some women without this, on its own, proving bacterial vaginosis.
Treatment should not be based solely on a “positive/negative” finding. The pathogen, symptoms, clinical examination and medical history must all be considered. The laboratory report also emphasises that the presence of a microorganism does not necessarily mean that it is the cause of the symptoms.
An accurate diagnosis comes before treatment
Vaginal infections and disturbances of the vaginal flora are not all treated in the same way.
Molecular testing can provide valuable information, provided that the result is assessed in the context of the clinical examination, rather than in isolation.
A gynaecological assessment is performed at the practice and, where indicated, a sample is collected for the appropriate laboratory testing.
Book an appointment
To arrange molecular testing of vaginal fluid, you can book your appointment online, specifying the special PCR test for 28 STIs here:
